Fix fortressone_config.h so default.fmf not needed

[drzel]

[23:42] Spoike: https://github.com/FortressOne/fteqw-code/blob/main/engine/common/fs.c#L3855
[23:44] Spoike: those things should be defined inside your game config (particularly the GAME_IDENTIFYINGFILES one), otherwise it'll just fall back into thinking its running whatever else it finds in the gamedir (read: Quake, due to id1/pak0.pak's presence)
[23:45] zel: so just #define GAME_IDENTIFYINGFILES fortress?
[23:47] Spoike: "fortress/pak0.pak","someotherpaththatmeansthebasedirisfortressone" or something. up to 4 strings
[23:47] zel: hrmm
[23:48] zel: so I'm planning to make the server assets mirror the client soon... so there's id/pak0.pak, tf28/pak0.pak, lq/pak0.pak, oq/pak0.pak and our fortress/pak0.pak
[23:48] Spoike: the other (slightly less reliable) option is to ensure that the expansion of GAME_SHORTNAME exists somewhere as a substring of your exe's name.
[23:48] zel: fo
[23:48] zel: it does
[23:48] Spoike: fo.exe
[23:48] zel: fortressone.exe
[23:48] zel: so I should make shortname fortressone
[23:48] zel: ?
[23:48] Spoike: that's not fo
[23:49] zel: fo is a substring of fortressone 😛
[23:49] zel: I must have misunderstood
[23:49] Spoike: sure, that'd get it
[23:49] Spoike: still better to get the identifying files to identify it too, of course
[23:49] zel: not quite understanding what identifying files means
[23:50] Spoike: fte supports lots of different games, quake, quake2, etc
[23:50] Spoike: if you run it from the quake2 directory then fte sees that there's some baseq2/pak0.pak file and configures itself for running quake2.
[23:51] Spoike: whereas if you run it from quake's directory then it sees id1/pak0.pak (or id1/quake.rc for people that insist on unpacking everything) and it configures itself for quake.
[23:52] Spoike: the identifying files just gives it a way to configure itself according to which files it finds in a prospective basedir
[23:53] Spoike: if you use eg the -quake or -quake2 args then it knows that the -basedir PATH is MEANT to be that respective game.
[23:53] Spoike: or, you can just put a default.fmf file inside the basedir to be explicit about everything.